Method of and means for increasing voltages



Nov. 3,1925.

I. J. THORP METHGD OF AND MEANS FOR INCREASING VOLTAGES Filed April 26, 1921 awwcwutoz [L]. Tin/72 Patented Nov. 3, 1925.

I. JAY monr, or marnnwoon,

NEW JERSEY, ASSIGNOR TO AMERICAN TELEPHONE I AND TELEGRAPH COMPANY, A CORPORATION OF NEW YORK.

men or Anni/mans ron INCREASING vouchers.

Application men Apri126, 1921. Serial No. 464,709.

To all whom it may concern:

Be it known that I, I.' J AY THORP,IeSl(l1Ilg at Maplewood, in the county of'Essex and State of New Jersey, have invented certain Improvements in Methods of and Means for Increasin Voltages, of which the following is a specification. v

This invention relates to arrangements for increasing or augmenting voltages applied from a source of potentialto a device associated therewith.

A specific instance in which the arrangements of the invention might be utilized would be in cases in which the amplification of low frequency currents is involved. With the arrangements of the invention the potential applied by such currents to the grid of a vacuum tube, amplifier may be materially increased and thus provide a greater degree of amplification. Furthermore these arrangements might be utilized to adv-an.- tage when itmight be desired tolmeasure variations in potential of" very weak currents. The method herein disclosed for increasing the voltage applied to a device, such as to the grid of a vacuum tube amplifier, employs? a variable capacity condenser. The condenser, whose plates are close together at the outset and whose capacity is therefore maximum, is first connected to the source of potential tobe am plified or measured so as to charge the condenser. The

plates of the condenser are then pulled apartso as to decrease the capacity while main-" taining the charge on the plate constant, thus increasing thevoltage, and the condenseris then applied to the grid of the amplifier'. In other, words mechanical energy devoted to the pulling apart of the con-' denser plates is translated and developed into an increase in the applied voltage.-

The invention may be more fully understood from the following description together with the. accompanyingdrawing in the Fig. .1 of. which is illustrated a circuit diagram of a preferred form of the invention and in Fig. 2 is shown graphically a curve illustrating the principles of. operation thereof a In Fig. 1 is shown a .vacuum bulb ampli-' fier A connected through he arrangements of the invention .to a sour 8 of potential.

The vacuum bulb contains a plate 2, a fila ment 3, and a grid 1. The grid is connected to a conductor 4 and the filament a con ductor 5. The source 8 is connected to conductor 5 and also to a conductor 7. Associ- 1 ated with the conductors 4, 5, and 7 are 'the fixed and are attached to conductor'o. As-

sociated with conductor 7 are points 13, 14, 15, and 16, and associated with conductor 4 are the contact points 17, 18, 19, and 20.

When the plates of one of the condensers are close together, as shown in the drawing for condenser 9, one of the contact points, such as contact 13, will be connected to the upper plate of thecondenser. As the lower plate is at the same time connected to conductor 5 the condenser will be charged. As the rotating shaft 21 revolves the upper plate of condenser 9 will bepulled away from the lower plate and'froin contact 13. The charge on the upper plate will remain constant but the pulling apart of the plates will decrease the capacity and thus increase the voltage on the upperplate. When the shaft 21 has revolved further-the upper plate of condenser 9 will come into contact plates of condensers 10 and 12 are shown in half opened plositions bythe' operation of shaft 21. As as been pointed out the pull-- ing apart of the plates of the condensers,

while maintaining the charge thereon con-' stant, will decrease the capacity but willincrease the volta e, so that with the arrangement shown w en the upper plates come into contact with the contact points 17, 18, 19 and 20 an increased potential will be applied to the grid ofthe amplifier.

the contact In Fig. 2 is shown an exponential timevoltage curve upon which are based the followingcalculations made to obtain an idea of the capacities which the condensers, such as 9, 10, 11, and 12, would need to have in order to effect a voltage amplification of 9 :1, assuming the ratio of maximum to minimum capacity of the condensers is 10 :1 and also assuming four condensers discharged at a rate of 1000 discharges per minute. Let t, be the time of discharge of each condenser A andi on 1 X .015 seconds.

. The equation of the curve is L o=Ve CR. 1

where 'v is .the variable voltage, V is the maximum voltage, e is the base of the Naperian logaritham, t is the time of discharge, G is the capacity of the circuit, and R is the resistance of the circuit.-

The time constant T of a circuit is by definition that value of the time t for which comes unity. In other words T is that value of the time t at which t r-CRand ;'.T=GR 2) Assume the average voltage from 0 to t,

on the curve to be .9 of the maximum, which maximumon the curve is given as 1.0

t Let -X 3 X being the proportion which 6 bears to the time constant T.

' Now since the average voltage during the I interval from time 0 to time t, is known and since from equation (1) the voltage at time T is 0- the value of X may be readily computed to be .215;

Then from equation. (3) it follows that. in order that the average voltage sliould'equal .9 of the maximum, the time constant T should besuch that r .015='r=:.2 15=1 and hence Y T= -=,07 seconds.

Assume that the grid leak equals 5 megohms. Now from equation (2) In other words the condensers should each in the equation (1) of the curve be-- Lesaee have a capacity of .OleLmicrofarads at the time of greatest separation to give a voltage amplification under the above conditions of 9:1.

While the arrangements of the invention."

have been shown as associated with a vacu um bulb amplifier, it is pointed out that they might equally welLbe utilized for increas' ing'potentials applied to other devices, F 11- thermore the number of condensers, the speed of operation, ,and capacities of the condensers may be varied if desired. Accordingly while the invention has been dis- 1 closed in certain arrangements which have been deemed desirable, it is understood that it is capable of embodiment in many and-- widely varied forms Without departing'from f r appended claims.

WVhat-is claimed is:

1. A source of potential, a device to voltage from said source is to be applied, a condenser having its plates connected to said source, mechanical meansffOr periodically and uniformly pulling one of the plates of said condenser away from the other while the spirit of the invention asdefined in the which maintaining'the charge thereon constant, and

means for discharging said con-denser plate on said device.

2. A source of potential, a device to which voltage from said source is to be applied,..a I

mechanically rotated shaft, and a plurality of condensers having their lower plates connected to said source and their upper plates connected to said. shaft, whereby said upper plates may be alternately connected to said source and .charged and may be moved-away from said lower plates and discharged on said device.

.3. A source'of potentlal, a vacuum tube 'device to the grid circuit of which voltage said condensers in rotation to the grid circuit of said vacuum tube whereby said plates may be discharged on said gridcircuit.

3 In testimony whereof, I have signed my name to this specification this 25th day of April, 1921. v e

I. JAY THORP. 

